Optical information recording medium, optical information recording method, and optical information recording apparatus

ABSTRACT

An information recording medium according to the present invention includes a plurality of recording layers, and a test area for determining a recording power of a laser light for each of the plurality of recording layers, in which a first test area of a first layer and a second test area of a second layer adjacent to the first layer are provided at different radial positions.

This application is a continuation application of U.S. application Ser.No. 11/857,785 filed Sep. 19, 2007, which is a continuation applicationof U.S. patent application Ser. No. 10/296,662 filed on Mar. 31, 2003,which is a §371 of International Application No. PCT/JP01/07927 filedSep. 12, 2001 and claims priority to Japanese Application No.2000-277775 filed on Sep. 13, 2000, the entire disclosures of which areincorporated herein by reference, and is related to sibling U.S.application Ser. Nos. 12/101,414, 12/101,434, 12/101,454, 12/101,472,12/101,496, 12/101,577 and 12/101,756 all now abandoned.

TECHNICAL FIELD

The present invention relates to an optical information recordingmedium, an optical information recording method and an opticalinformation recording apparatus, for optically recording information. Inmore detail, the present invention relates to an optical informationrecording medium including a first information recording layer on whichinformation is to be recorded by laser light and a second informationrecording layer on which information is to be recorded by the laserlight which has passed through the first information recording layer;and a method and an apparatus for the optical information recordingmedium.

BACKGROUND ART

Recently, optical discs, optical cards, optical tapes and the like havebeen developed as optical information recording media for allowinginformation to be optically recorded. Among these, optical discs haveattracted attention as optical information recording media for allowinga large capacity of information to be recorded at high density.

One type of rewritable discs are phase-change optical discs. A recordinglayer used for a phase-change optical disc is reversibly changed toeither an amorphous state or a crystalline state, depending on theconditions of heating by laser light and the cooling conditions. Therecording layer has different optical constants when in an amorphousstate from when in a crystalline state. Therefore, in the case of aphase-change disc, one of the two states is selectively formed in therecording layer in accordance with information to be recorded, and theresultant optical change (i.e., a change in transmittance orreflectance) is utilized. Thus, information recording and/orreproduction can be performed. In order to obtain the two states,information is recorded as follows.

A recording layer of an optical disc is irradiated with pulse-type laserlight (referred to as a “recording pulse”) at a power for raising thetemperature of the recording layer to equal to or higher than themelting point. As the laser light passes, the melted portion of therecording layer is rapidly cooled into a recording mark in an amorphousstate. Alternatively, the recording layer is irradiated with focusedlaser light at a power for raising the temperature of the recordinglayer to a point equal to or higher than the crystallization point butequal to or lower than the melting point. Then, the portion of therecording layer irradiated with the laser light is placed into acrystalline state.

An optical disc is a recording medium which is exchangeably mounted withother optical discs on an optical disc recording and reproductionapparatus. Therefore, the optical disc recording and reproductionapparatus needs to stably perform recording on or reproduction from aplurality of optical discs. Even optical discs produced under the sameconditions may have different recording mark states or may bedifferently influenced by thermal interference between recording marks,due to different thermal characteristics thereof which are caused bydispersions at the time of production and/or time-wise changes. This mayresult in different recording conditions including the recording powerfor the optical disc and the optimum edge position of the recordingpulse.

In order to stably record information without being influenced bychanges in such recording conditions, an optical disc recording andreproduction apparatus obtains recording conditions before recordinginformation on an optical disc. Specifically, before recordinginformation on an optical disc, an optical recording and reproductionapparatus performs test recording using a specific data pattern(referred to as “test information”), reproduces the test information,and measures the reproduced signal so as to obtain the recordingcondition. This process is referred to as “test recording”. Opticaldiscs have an area used by the test recording, which is referred to asan “test recording area”.

A rewritable disc has a reproduction-only area pre-formed in a specificportion. The reproduction-only area includes convex and concave phasepits. In the reproduction-only area, information which does not need tobe rewritten, for example, information on the optical disc itself oraddress information, is recorded. This area is also referred to as an“emboss area”.

An area in which information is recorded by forming a recording mark isreferred to as a “recording and reproduction area”. In the recording andreproduction area, information which has a possibility of beingrewritten is recorded.

A general rewritable optical disc has a data area in a central portionin a radial direction thereof, and has a lead-in area in a portioninternal with respect to the data area, and a lead-out area in a portionexternal with respect to the data area. In general, an area forrecording management information of the optical disc and/or a testrecording area is provided in the lead-in area and the lead-out area.

Recently, there has been strong demand for the optical discs with ahigher recording density. In response to this demand, a multi-layerrecording medium having two or more information recording layers in athickness direction of the disc is proposed. Information can be recordedon each of the information recording layers.

In such a multi-layer recording medium, each of the informationrecording layers often have different recording characteristics. Thisrequires test recording to be performed for each information recordinglayer. One exemplary method of such test recording is disclosed inJapanese Laid-Open Publication No. 11-3550.

However, conventional methods do not consider the following phenomenon.When test recording is performed on an information recording layer of amulti-layer recording medium which is far from the laser incidencesurface (the information recording layer far from the laser incidencesurface will be referred to as a “second information recording layer”),the second information recording layer is influenced by the state of aninformation recording layer which is closer to the laser incidencesurface (the information recording layer closer to the laser incidencesurface will be referred to as a “first information recording layer”).

Laser light used for recording information on the second informationrecording layer may become non-uniform when the laser light has passedthrough a certain area of the first information recording layer. In thiscase, test recording would not provide accurate recording conditions.

The light transmittance of an information recording layer variesdepending on whether information is recorded or not in the recording andreproduction area of the information recording layer. Therefore, theamount of laser light reaching the second information recording layervaries in accordance with the ratio of an unrecorded area and a recordedarea in a light spot of the laser light on the first informationrecording layer, the light spot being formed before the laser light isused for test recording on the second information recording layer. As aresult, accurate recording conditions are not obtained.

The light transmittance of an unrecorded area in the recording andreproduction area can be considered to be equal to the lighttransmittance of the reproduction-only area. However, the lighttransmittance of a recorded area in the recording and reproduction areais different from the light transmittance of the reproduction-only area.Accordingly, when test recording is performed on the second informationrecording layer, the amount of laser light reaching the secondinformation recording layer varies also in accordance with the ratio ofthe reproduction-only area and the recording and reproduction area in alight spot on the first information recording layer (and the ratio ofthe recorded area and the unrecorded area in the recording andreproduction area).

The second information recording layer is influenced by the state of thefirst information recording layer when information (for example, userdata information) is recorded in a recording and reproduction area ofthe second information recording layer, as well as at the time of testrecording. In this case also, information cannot be accurately recorded,which reduces the signal quality used for reproducing the recordedinformation.

The present invention, to solve these problems of the prior art, has anobjective of accurately obtaining optimum recording conditions for anoptical information recording medium having two or more informationrecording layers, and another objective of accurately recordinginformation on each of two or more information recording layers of anoptical information recording medium.

DISCLOSURE OF THE INVENTION

An optical information recording medium according to the presentinvention includes a first information recording layer on whichinformation is to be recorded by laser light; and a second informationrecording layer on which information is to be recorded by the laserlight which has passed through the first information recording layer.The first information recording layer includes at least one of areproduction-only area and a recording and reproduction area. The secondinformation recording layer includes a test recording area. At least oneof the reproduction-only area and the recording and reproduction area,and the test recording area is located such that one of thereproduction-only area and the recording and reproduction area includesan area of the first information recording layer through which the laserlight for recording information in the test recording area passes.

The optical information recording medium may further include aseparation layer for separating the first information recording layerand the second information recording layer from each other. The area ofthe first information recording layer, through which the laser light forrecording information in the test recording area passes, may extendoutward from an outer end of an area of the first information recordinglayer corresponding to the test recording area by a length δ, the lengthδ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The second information recording layer may have a data recording areawhich extends from an end of the test recording area by at least thelength δ.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area passes,may extend outward from the outer end of the area of the firstinformation recording layer corresponding to the test recording area bya length δ′, the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

The second information recording layer may include a data recording areawhich extends from the end of the test recording area by at least thelength δ′.

An optical information recording medium according to the presentinvention includes a first information recording layer on whichinformation is to be recorded by laser light; and a second informationrecording layer on which information is to be recorded by the laserlight which has passed through the first information recording layer.The first information recording layer includes a prescribed area. Thesecond information recording layer includes a test recording area. Theprescribed area and the test recording area are located such that theprescribed area includes an area of the first information recordinglayer through which the laser light for recording information in thetest recording area passes. The prescribed area is entirely in arecorded state or entirely in an unrecorded state.

The prescribed area, when being in an unrecorded state, may be arecording prohibited area.

The prescribed area, when being in an unrecorded state, may be a mirrorarea.

The prescribed area, when being in an unrecorded state, may be a lead-inarea.

The optical information recording medium may further include aseparation layer for separating the first information recording layerand the second information recording layer from each other. The area ofthe first information recording layer, through which the laser light forrecording information in the test recording area passes, may extendoutward from an outer end of an area of the first information recordinglayer corresponding to the test recording area by a length δ, the lengthδ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The second information recording layer may have a data recording areawhich extends from an end of the test recording area by at least thelength δ.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area passes,may extend outward from the outer end of the area of the firstinformation recording layer corresponding to the test recording area bya length δ′, the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

The second information recording layer may include a data recording areawhich extends from the end of the test recording area by at least thelength δ′.

An optical information recording medium according to the presentinvention includes a first information recording layer on whichinformation is to be recorded by laser light; and a second informationrecording layer on which information is to be recorded by the laserlight which has passed through the first information recording layer.The first information recording layer includes a test recording area anda recording and reproduction area. A light transmittance of an area ofthe first information recording layer, through which the laser light forrecording information in the test recording area passes, is differentfrom a light transmittance of an area of the first information recordinglayer, through which the laser light for recording information in therecording and reproduction area passes. Information for calculating anoptimum recording condition of at least one of the test recording areaand the recording and reproduction area is recorded in a specific areaof either the first information recording layer or the secondinformation recording layer.

An optical information recording medium according to the presentinvention includes a first information recording layer on whichinformation is to be recorded by laser light; and a second informationrecording layer on which information is to be recorded by the laserlight which has passed through the first information recording layer.The first information recording layer includes at least one of areproduction-only area and a first recording and reproduction area. Thesecond information recording layer includes a second recording andreproduction area. At least one of the reproduction-only area and thefirst recording and reproduction area, and the second recording andreproduction area are located such that one of the reproduction-onlyarea and the first recording and reproduction area includes an area ofthe first information recording layer through which the laser light forrecording information in the second recording and reproduction areapasses.

The optical information recording medium may further include aseparation layer for separating the first information recording layerand the second information recording layer from each other. The area ofthe first information recording layer, through which the laser light forrecording information in the second recording and reproduction areapasses, may extend outward from an outer end of an area of the firstinformation recording layer corresponding to the second recording andreproduction area by a length δ, the length δ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the secondrecording and reproduction area.

The area of the first information recording layer, through which thelaser light for recording information in the second recording andreproduction area passes, may extend outward from the outer end of thearea of the first information recording layer corresponding to thesecond recording and reproduction area by a length δ′, the length δ′being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

A size of the reproduction-only area of the first information recordinglayer may be zero.

An optical information recording medium according to the presentinvention includes a first information recording layer on whichinformation is to be recorded by laser light; a second informationrecording layer on which information is to be recorded by the laserlight which has passed through the first information recording layer;and a separation layer for separating the first information recordinglayer and the second information recording layer from each other. Thefirst information recording layer includes at a first test recordingarea and a non-uniform light prevention area. The second informationrecording layer includes a second test recording area. The non-uniformlight prevention area, the first test recording area and the second testrecording area are located, such that a distance between the first testrecording area and the second test recording area is greater than alength δ, and such that the non-uniform light prevention area includesan area of the first information recording layer through which the laserlight for recording information in the second test recording areapasses, the length δ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the secondtest recording area.

The first information recording layer may include at least one of afirst lead-in area and a first lead-out area. The second informationrecording layer may include at least one of a second lead-in area and asecond lead-out area. The first lead-in area and the second lead-in arearespectively may include the first test recording area and the secondtest recording area, or the first lead-out area and the second lead-outarea respectively include the first test recording area and the secondtest recording area.

The non-uniform light prevention area of the first information recordinglayer may be a reproduction-only area.

The non-uniform light prevention area may be an area formed of at leastone of the group consisting of a reproduction-only area, a recordingprohibited area, and a mirror area.

The area of the first information recording layer, through which thelaser light for recording information in the second test recording areapasses, may extend outward from an outer end of an area of the firstinformation recording layer corresponding to the second test recordingarea by a length δ′, the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

The area of the first information recording layer, through which thelaser light for recording information in the second test recording areapasses, may extend outward from an outer end of an area of the firstinformation recording layer corresponding to the second test recordingarea by a length δ′, the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

An optical information recording method according to the presentinvention is for an optical information recording medium including afirst information recording layer on which information is to be recordedby laser light; and a second information recording layer on whichinformation is to be recorded by the laser light which has passedthrough the first information recording layer. The first informationrecording layer includes at least one of a reproduction-only area and arecording and reproduction area. The second information recording layerincludes a test recording area. The optical information recording methodincludes the steps of recording information, in advance, in an area ofthe first information recording layer, through which the laser light forrecording information in the test recording area is to pass; andrecording the information in the test recording area after the step ofrecording the information in advance.

The optical information recording method may further include aseparation layer for separating the first information recording layerand the second information recording layer from each other. The area ofthe first information recording layer, through which the laser light forrecording information in the test recording area passes, may extendoutward from an outer end of an area of the first information recordinglayer corresponding to the test recording area by a length δ, the lengthδ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area passes,may extend outward from the outer end of the area of the firstinformation recording layer corresponding to the test recording area bya length δ′, the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

The information which is recorded in advance may be information obtainedby modulating dummy information.

The step of recording the information in advance may include the step ofrecording using a certification step.

An optical information recording method according to the presentinvention is for an optical information recording medium including afirst information recording layer on which information is to be recordedby laser light; and a second information recording layer on whichinformation is to be recorded by the laser light which has passedthrough the first information recording layer. The first informationrecording layer includes at least one of a reproduction-only area and arecording and reproduction area. The second information recording layerincludes a test recording area. The optical information recording methodincludes the steps of determining whether an area of the firstinformation recording layer, through which the laser light for recordinginformation in the test recording area passes, is an area of one of thereproduction-only area and the recording and reproduction area which isan unrecorded state or an area of the recording and reproduction areawhich is in a recorded state; executing test recording in the testrecording area so as to obtain a recording condition; and calculating anoptimum recording condition for the second information recording layerbased on the result of the determination and the obtained recordingcondition.

The optical information recording medium may further include aseparation layer for separating the first information recording layerand the second information recording layer from each other. The area ofthe first information recording layer, through which the laser light forrecording information in the test recording area passes, may extendoutward from an outer end of an area of the first information recordinglayer corresponding to the test recording area by a length δ, the lengthδ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the secondrecording and reproduction area.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area passes,may extend outward from the outer end of the area of the firstinformation recording layer corresponding to the test recording area bya length δ′, the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

The information for calculating the optimum recording condition may berecorded in a specific area of the first information recording layer andthe second information recording layer.

An optical information recording apparatus according to the presentinvention is for an optical information recording medium including afirst information recording layer on which information is to be recordedby laser light; and a second information recording layer on whichinformation is to be recorded by the laser light which has passedthrough the first information recording layer. The second informationrecording layer includes a test recording area. The optical informationrecording apparatus includes an interference area determination sectionfor determining an area of the first information recording layer throughwhich the laser light for recording information in the test recordingarea passes; a recorded/unrecorded state determination section fordetermining whether the area of the first information recording layer,through which the laser light for recording information in the testrecording area passes, is in a recorded state or in an unrecorded state;and a recording section for recording a signal in the area of the firstinformation recording layer, through which the laser light for recordinginformation in the test recording area passes, based on the results ofthe determination of the interference area determination section and therecorded/unrecorded state determination section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an external view of an optical information recording mediumaccording to the present invention.

FIG. 2 is a cross-sectional view of the optical information recordingmedium according to the present invention.

FIG. 3 shows a format of a first information recording layer and asecond information recording layer according to Example 1 of the presentinvention.

FIG. 4 shows a format of a first information recording layer and asecond information recording layer of a comparative example.

FIG. 5 shows the length of a light spot of the first informationrecording layer (i.e., an area of the first information recording layer,through which laser light passes) according to the present invention.

FIG. 6 shows a format of a first information recording layer and asecond information recording layer according to a modified example ofExample 1.

FIG. 7 shows a format of a first information recording layer and asecond information recording layer according to Example 2 of the presentinvention.

FIG. 8 shows a format of a first information recording layer and asecond information recording layer according to Example 3 of the presentinvention.

FIG. 9 is a block diagram of an optical information recording apparatusfor creating an optical information recording medium according toExample 3 of the present invention.

FIG. 10 shows a format of a first information recording layer and asecond information recording layer according to Example 4 of the presentinvention.

FIG. 11 shows a format of a first information recording layer and asecond information recording layer according to Example 5 of the presentinvention.

FIG. 12 shows a format of a first information recording layer and asecond information recording layer according to Example 6 of the presentinvention.

FIG. 13 shows a format of a plurality of information recording layersaccording to Example 7 of the present invention.

FIG. 14 shows a format of a first information recording layer and asecond information recording layer according to Example 8 of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by way ofillustrative examples with reference to attached drawings.

Example 1

This example relates to an optical information recording medium withwhich accurate recording conditions can be obtained by the testrecording.

FIG. 1 is an external view of an optical information recording medium100 according to the present invention. Hereinafter, the optical disc100 will be used as a specific example of the optical informationrecording medium 100.

FIG. 2 is a cross-sectional view illustrating a structure of the opticalinformation recording medium or the optical disc 100. The optical disc100 has a multi-layer structure. As shown in FIG. 2, the optical disc100 includes an incidence surface 110, a first information recordinglayer 120, a second information recording layer 130, and a separationlayer 150 for separating the first information recording layer 120 andthe second information recording layer 130 from each other.

The first information recording layer 120 and the second informationrecording layer 130 are formed by pre-forming a groove or a phase pit ina first substrate 140 and a second substrate 145 respectively, and thenforming a protective layer, a recording layer, a reflective layer andthe like thereon. The resultant first substrate 140 and the resultantsecond substrate 145 are bonded together with an ultraviolet-curableresin or the like, so as to form the separation layer 150. Theseparation layer 150 separates the first information recording layer 120and the second information recording layer 130 from each other.

Laser light 170 is focused by an objective lens 160 and then is incidenton the incidence surface 110. The laser light 170 records information onthe information recording layers. FIG. 2 shows a state where informationis recorded on the second information recording layer 130 by the laserlight 170 which has passed through the first information recording layer120.

Next, a format of the optical disc 100 used in this example will bedescribed.

FIG. 3 shows a format of the first information recording layer 120 andthe second information recording layer 130. FIG. 3 shows the format in aradial direction of the disc from the center of the optical disc 100.The center of the optical disc 100 is represented by “0” in the radialdirection. The distance along the arrow labeled as “radial direction”indicates distance from the center of the optical disc 100. The leftside of the figure represents the inner side of the optical disc 100,and the right side of the figure represents the outer side of theoptical disc 100. In FIG. 3, it is assumed that laser light is directedtoward the optical disc 100 from the bottom portion of the figure.

The first information recording layer 120 includes a firstreproduction-only area (ROM) 122 and a first recording and reproductionarea (RAM) 124. The first recording and reproduction area 124 includes afirst test recording area (TEST) 126 and a first data recording area(DATA) 128. In FIG. 3, the first information recording layer 120includes the first reproduction-only area 122, the first test recordingarea 126, and the first data recording area 128 in that order from theinner portion thereof.

The second information recording layer 130 includes a secondreproduction-only area (ROM) 132 and a second recording and reproductionarea (RAM) 134. The second recording and reproduction area 134 includesa second test recording area (TEST) 136 and a second data recording area(DATA) 138. An area 133 between the second-reproduction-only area 132and the second test recording area 136 is, for example, an unused areawhich has not been used. In FIG. 3, the second information recordinglayer 130 includes the second reproduction-only area 132, the unusedarea 133, the second test recording area 136, and the second datarecording area 138 in that order from the inner portion thereof.

In the first reproduction-only area 122 and the second reproduction-onlyarea 132, a phase pit array representing information is formed. In thefirst recording and reproduction area 124 and the second recording andreproduction area 134, grooves representing information are formed.

In this specification, it is assumed that in a reproduction-only area,information which does not need to be rewritten, for example,information of the optical disc itself or address information, isrecorded. By contrast, it is also assumed that in a recording andreproduction area, information which has a high possibility of beingrewritten is recorded. Since different types of information are recordedin the reproduction-only area and in the recording and reproductionarea, the information is recorded in different forms in thereproduction-only area and in the recording and reproduction area asdescribed above. In the reproduction-only area, information which doesnot need to be rewritten is recorded. Therefore, such information isrecorded with a phase pit array, simultaneously with the formation ofthe substrate. In the recording and reproduction area, information whichhas a high possibility of being rewritten is recorded. Therefore,information is recorded in the form of a recording mark on the recordinglayer which is formed on the grooves.

In this specification, a test recording area is used for performing testrecording on the information recording layer including the testrecording area. A data recording area is used for recording user datainformation.

In this example, the first information recording layer 120 and thesecond information recording layer 130 are provided from the center ofthe disc substantially parallel to each other and have substantially thesame length as each other.

Throughout this specification, for easier understanding of theinvention, when the optical information recording medium includes twoinformation recording layers, the information recording layer which iscloser to the incidence side of the optical information recording mediumis referred to as the “first information recording layer”, and theinformation recording layer which is farther from the incidence side ofthe optical information recording medium is referred to as the “secondinformation recording layer”. As described in detail below, the numberof the information recording layers of the optical information recordingmedium is not limited to two. The present invention is applicable to anoptical information recording medium having a plurality of informationrecording layers.

Returning to FIG. 3, the format of the optical disc 100 will bedescribed.

The first recording and reproduction area 124 of the first informationrecording layer 120 extends from position r1 to an outer periphery ofthe optical disc 100.

The second test recording area 136 of the second information recordinglayer 130 extends from position r2 by distance a.

The start point of the first recording and reproduction area 124 iscloser to the center of the disc by length δ than the start point of thesecond test recording area 136. In this specification, a “start point”of an area refers to the point in an area having the shortest distancefrom the center of the disc, and a “termination point” of an area refersto the point in an area having the longest distance from the center ofthe disc.

Here, it is assumed that information is recorded in the second testrecording area 136 in order to perform test recording of the secondinformation recording layer 130.

The laser light 170 for recording information in the second testrecording area 136 passes through the first information recording layer120. Since the laser light 170 is focused after being incident, an area(light spot) 175 of the first information recording layer, through whichthe laser light 170 passes, is larger than the second test recordingarea 136. In this example, the optical disc 100 is structured such thatthe first recording and reproduction area 124 includes the area 175 ofthe first information recording layer 120 through which the laser light170 passes for recording information in the second test recording area136. For this reason, the start point of the first recording andreproduction layer 124 is closer to the center of the disc by length δthan the start point of the second test recording area 136. In FIG. 3,only the laser light 170 incident in a portion internal to the secondtest recording area 136 is considered. The reason is that, since in thisstructure, the first recording and reproduction area 124 extends fromthe start point of the first test recording area 126 to the outerperiphery of the disc, it is not necessary to consider the laser light170 incident in a portion external to the second test recording area136.

The length of the area 175 of the first information recording layer 120,through which the laser light 170 which is to be focused in the secondtest recording area 136 passes, equals δ+a+δ. Namely, the area 175includes an area corresponding to the second test recording area 136having the length a and two areas respectively extending from an innerend and an outer end of the above-mentioned area toward the center ofthe disc and the outer periphery of the disc, each extending area havinglength δ. As described above, such a size of the area 175 results fromthe fact that the diameter of the spot of the laser light 170 at thefirst information recording layer 120 is greater than that at the secondinformation recording layer 130. In the case where the first recordingand reproduction area 124 and the second test recording area 136 arelocated such that the first recording and reproduction area 124 includesat least the area 175, the laser light 170 passes through only the firstrecording and reproduction area 124 when passing through the firstinformation recording layer 120 in the test recording performed usingthe second test recording area 136.

As described above, the first recording and reproduction area 124 andthe second test recording area 136 are located such that the laser light170 passes through only the first recording and reproduction area 124when passing through the first information recording layer 120 in thetest recording performed on the second test recording area 136. Thereasons are as follows.

A recording and reproduction area and a reproduction-only area areformed in different forms. Therefore, the light transmittance of therecording and reproduction area may sometimes be different from thelight transmittance of the reproduction-only area. When laser lightpasses through both the reproduction-only area and the recording andreproduction area in this, case, a component of light passing throughthe reproduction-only area and reaching the second information recordinglayer and a component of light passing through the recording andreproduction area and reaching the second information recording layerwill have different amounts.

The light transmittance of an unrecorded area in the recording andreproduction area can be considered to be equal to the lighttransmittance of the reproduction-only area. However, when the recordingand reproduction area has information recorded therein, the lighttransmittance of a recorded area in the recording and reproduction areais different from the light transmittance of the reproduction-only area.Accordingly, when information is recorded in the recording andreproduction area of the first information recording layer, the lighttransmittance is different between the reproduction-only area 122 andthe recording and reproduction area 124 of the first informationrecording layer 120.

In a recording and reproduction area, a recording mark (in an amorphousstate) is formed. When the recording mark is formed, the lighttransmittance of the recording and reproduction area is raised in somecases and is reduced in other cases. Hereinafter, the case where thelight transmittance is raised will be described. In this case, theamount of light transmitted through the recording and reproduction areais larger than amount of light transmitted through the reproduction-onlyarea.

For comparison, FIG. 4 shows a format of an optical disc 400 in which afirst information recording layer and a second information recordinglayer have the same format.

The optical disc 400 includes a first information recording layer 420, asecond information recording layer 430, and a separation layer 450 forseparating the first information recording layer 420 and the secondinformation recording layer 430 from each other.

The first information recording layer 420 includes a firstreproduction-only area (ROM) 422 and a first recording and reproductionarea (RAM) 424. The first recording and reproduction area 424 includes afirst test recording area (TEST) 426 and a first data recording area(DATA) 428.

The second information recording layer 430 includes a secondreproduction-only area (ROM) 432 and a second recording and reproductionarea (RAM) 434. The second recording and reproduction area 434 includesa second test recording area (TEST) 436 and a second data recording area(DATA) 438.

In this comparative example, the format of the first informationrecording layer 420 is the same as that of the second informationrecording layer 430. Therefore, the start point r1′ of the firstrecording and reproduction area 424 is the same as the start point r2′of the second test recording area 436.

In this case, when laser light 470 is incident on the innermost portionof the second test recording area 436 (i.e., the left end of the secondtest recording area 436 as shown in FIG. 4) for test recording of thesecond information recording layer 430, half of the laser light 470incident on the first information recording layer 420 is transmittedthrough the first reproduction-only area 422.

As a result, the amount of laser light 470 passing through the firstreproduction-only area 422 and reaching the second information recordinglayer 430 is different from the amount of laser light 470 passingthrough the first recording and reproduction area 424 and reaching thesecond information recording layer 430. Therefore, accurate testrecording cannot be performed. For example, when the light transmittanceof the recording and reproduction area is higher than the lighttransmittance of the reproduction-only area, recording power which isgreater than the recording power of the laser light passing through thereproduction-only area is determined to be the desired recording power.

Accordingly, when test recording is performed using the innermostportion of the second test recording area 436 (i.e., the left end of thesecond test recording area 436 in FIG. 4) in order to obtain the desiredrecording power, recording power which is greater than the appropriaterecording power is provided as the result of the test recording result.Therefore, actual data is recorded at excessively high recording power.

Moreover, the amount of the laser light 470 reaching the secondinformation recording layer 430 varies in accordance with the ratio ofthe laser light 470 transmitted through the first reproduction-only area422 with respect to the entire laser light 470 used for recordinginformation in the second test recording area 436. As a result, the testrecording result varies in accordance with the position of the secondtest recording area 436 in which information is recorded.

By contrast, with the format according to this example shown in FIG. 3,the laser light 170 is not influenced by the first reproduction-onlyarea 122 regardless of the position in the second test recording area136 at which test recording is performed. Accordingly, accuraterecording conditions are obtained by the test recording.

Hereinafter, with reference to FIG. 5, expansion of the light spot 175on the first information recording layer 120 will be described indetail. FIG. 5 shows the length of the light spot 175 on the firstinformation recording laser 120 when the laser light 170 is focused onthe second information recording layer 130. Here, for simplerexplanation, the laser light 170 is focused onto a focal point 172 onthe second information recording layer 130. In this state, the angle θat which the laser light 170 is focused onto the focal point 172 is:

θ=sin⁻¹(NA/n).

Where the distance in the thickness direction of the disc between thefirst information recording layer 120 and the second informationrecording layer 130 is d, the numerical aperture of the objective lens160 is NA, and the refractive index of the separation layer 150 is n,the radius δ of the light spot 175 on the first information recordinglayer 120 is represented by:

δ=d·tan θ=d·tan(sin⁻¹(NA/n)).

From this, as long as the start point of the first test recording area126 in FIG. 3 is away from the start point of the second test recordingarea 136 by at least length δ represented by the above expression, thefirst recording and reproduction area 124 includes the light spot 175 ofthe laser light 170 on the first information recording layer 120. Inthis case, accurate recording conditions can be obtained by the testrecording.

As described above, the optical information recording medium 100according to this example is structured such that the first recordingand reproduction area 124 includes the area 175 of the first informationrecording layer 120 of the laser light 170 for recording information inthe second test recording area 136 passes. Therefore, accurate recordingconditions can be obtained by the test recording.

In FIG. 3, the area between the second reproduction-only area 132 andthe second test recording area 136 is the unused area 133. The presentinvention is not limited to this.

For example, as shown in FIG. 6, the unused area 133 may be replacedwith a third data recording area 137. In this case, the length of thedata recording area 137 is at least equal to length δ. An optical disc600 shown in FIG. 6 has the same format as that of the optical disc 100shown in FIG. 3 except that the unused area 133 is replaced with thethird data recording area 137. Such a format can expand the datarecording area compared to that of the disc 100 shown in FIG. 3.

Example 2

In this example, a case where the center of the two informationrecording layers are offset with respect to each other will bedescribed.

In actual production of a multi-layer recording medium, a plurality ofinformation recording layers may be sometimes positionally offset withrespect to each other when the information recording layers are bondedtogether. When the start points of the test recording areas are offsetwith respect to each other due to the positional offset between theinformation recording layers, the length δconsidered in Example 1 is notsufficient. In this example, the effect of the present invention isprovided even when the distances of the two information recording layersfrom the center of the disc are different from each other.

FIG. 7 shows a format of an optical disc 700 in which a firstinformation recording layer 720 and a second information recording layer730 are offset with respect to each other by δm.

The optical disc 700 includes the first information recording layer 720,the second information recording layer 730, and a separation layer 750for separating the first information recording layer 720 and the secondinformation recording layer 730 from each other.

The first information recording layer 720 includes a firstreproduction-only area (ROM) 722 and a first recording and reproductionarea (RAM) 724. The first recording and reproduction area 724 includes afirst test recording area (TEST) 726 and a first data recording area(DATA) 728. In FIG. 7, the first information recording layer 720includes the first reproduction-only area 722, the first test recordingarea 726, and the first data recording area 728 in that order from theinner portion thereof.

The second information recording layer 730 includes a secondreproduction-only area (ROM) 732 and a second recording and reproductionarea (RAM) 734. The second information recording layer 730 may includean unused area 733. The second recording and reproduction area 734includes a second test recording area (TEST) 736 and a second datarecording area (DATA) 738. In FIG. 7, the second information recordinglayer 730 includes the second reproduction-only area 732, the unusedarea 733, the second test recording area 736, and the second datarecording area 738 in that order from the inner portion thereof.

In this figure, the offset δ′ between the start points of the firstrecording and reproduction area 724 and the second test recording area736, the offset δ′ being defined from the center of the disc, isrepresented by:

δ′=r2−r1=δ+δm=d·tan(sin⁻¹(NA/n))+δm.

This represents a value obtained by adding the length δ of the lightspot 725 on the first information recording layer 720 described inExample 1 with the length δm of the positional offset between the firstinformation recording layer 720 and the second information recordinglayer 730.

Accordingly, as long as the start of the first recording andreproduction area 724 is away from the start of the second testrecording area 736 by at least the length δ′ represented by the aboveexpression, the first recording and reproduction area 724 includes alight spot 775 on the first information recording layer 720, throughwhich laser light 770 passes, even when the first information recordinglayer 720 and the second information recording layer 730 arepositionally offset with respect to each other by the length δm.

Considering the difference in the distances of the first informationrecording layer 720 and the second information recording layer 730 fromthe center of the disc, it is necessary that the first recording andreproduction area 724 includes the area 775. Here, the area 775 is anarea of the first information recording layer 720 through which thelaser light 770 used for recording information on the second testrecording area 736 passes. The length of the area 775 needs to be atleast δ′+a+δ′. Namely, the area 775 includes an area corresponding tothe second test recording area 736 having the length a and two areasrespectively extending from an inner end and an outer end of theabove-mentioned area toward the center of the disc and the outerperiphery of the disc, each extending area having length δ′. In the casewhere the first recording and reproduction area 724 and the second testrecording area 736 are located such that the first recording andreproduction area 724 includes the area 775, accurate recordingconditions can be obtained by the test recording.

Example 3

In this example, a case where the area of the first informationrecording layer, through which laser light used for recordinginformation in the test recording area of the second informationrecording layer passes, is a recorded state area will be described.

FIG. 8 shows a format of an optical disc 800 according to this example.

The optical disc 800 includes a first information recording layer 820, asecond information recording layer 830, and a separation layer 850 forseparating the first information recording layer 820 and the secondinformation recording layer 830 from each other.

The first information recording layer 820 includes a firstreproduction-only area 822 and a first recording and reproduction area824. The first recording and reproduction area 824 includes a first testrecording area 826 and a first data recording area 828. In FIG. 8, thefirst information recording layer 820 includes the firstreproduction-only area 822, the first test recording area 826, and thefirst data recording area 828 in that order from the inner portionthereof.

The second information recording layer 830 includes a secondreproduction-only area 832 and a second recording and reproduction area834. The second recording and reproduction area 834 includes a secondtest recording area 836 and a second data recording area 838. An area833 between the second reproduction-only area 832 and the second testrecording area 836 is, for example, an unused area which has not beenused. In FIG. 8, the second information recording layer 830 includes thesecond reproduction-only area 832, an unused area 833, the second testrecording area 836, and the second data recording area 838 in that orderfrom the inner portion thereof.

In the optical disc 800, the first recording and reproduction area 824includes a recorded state area 875 of the first information recordinglayer 820. Laser light 870, used for recording information in the secondtest recording area 836, passes through the recorded state area 875. Therecorded state area 875 is entirely in a recorded state. The length ofthe recorded state area 875 is δ+a+δ. Namely, the recorded state area875 includes an area corresponding to the second test recording area 836having the length a and two areas respectively extending from an innerend and an outer end of the above-mentioned area toward the center ofthe disc and the outer periphery of the disc, each extending area havinglength δ.

The recorded state area 875 is formed by recording information in theentirety of the recorded state area 875 of the first recording andreproduction area 824, for example, before the second test recordingarea 836 is used.

Owing to such a structure, onto whichever position of the second testrecording area 836 the laser light 870 may be focused, the lighttransmittance of the area of the first recording and reproduction area824, through which the laser light 870 passes (i.e., area 875), can beuniform.

The light transmittance varies depending on whether information isrecorded or not in the recording and reproduction area 824. Since thearea 875 is entirely in a recorded state, the light transmittance isuniform. Accordingly, as long as information is recorded in the recordedstate area 875 shown in FIG. 8, the amount of the laser light 870reaching the second test recording area 836 is uniform when testrecording is performed on the second test recording area 836. As aresult, accurate recording conditions can be obtained.

In this example, when the first information recording layer 820 and thesecond information recording layer 830 are positionally offset withrespect to each other, the length of the recorded state area 875 mayhave the length δ′+a+δ′ as described in Example 2.

The information to be recorded in the recorded state area 875 may beinformation obtained by modulating data information or informationobtained by modulating dummy information.

It is preferable to record information in the recorded state area 875 atthe time of certification after the optical disc is produced. Since therecording apparatus does not need to perform this step, the start timewhen a new optical disc is mounted on the recording apparatus can beshortened.

Next, an optical recording apparatus for recording information on theoptical information recording medium according to this example will bedescribed.

FIG. 9 shows an optical information recording apparatus 900 for creatingthe optical information recording medium according to this example.Hereinafter, an operation of the optical information recording apparatus900 will be described with reference to FIG. 9.

The optical information recording apparatus 900 includes a spindle motor907 for rotating the optical disc 800 and an optical head 903 includinga laser source (not shown) and focusing laser light to a desiredposition of an information recording layer of the optical disc 800. Theentire operation of the optical information recording apparatus 900 iscontrolled by a system control section 901. It is not intended that therecorded state area 875 of the optical disc 800 is in a completelyrecorded state at this point.

The optical information recording apparatus 900 further includes arecording section 902 for modulating the light intensity of the lasersource in the optical head 903 based on information obtained bymodulating data information, and a reproduction section 904 forperforming waveform processing of a reproduction signal based on thelight reflected by the optical disc 800 so as to demodulate reproductioninformation. The optical information recording apparatus 900 alsoincludes an interference area determination section 905 for determiningwhether or not a given area of the first information recording layer 820is an area which can be an optical path of the laser light 870 forrecording information in the second test recording area 836 (i.e.,whether or not the given area is the area 875 through which the laserlight passes for recording information in the second test recording area836), and a recorded/unrecorded state determination section 906 forreproducing the information in the area 875 through which the laserlight passes for recording information in the second test recording area836 and then determining whether the area 875 is in a recorded state oran unrecorded state based on the reproduction result.

Hereinafter, with reference to FIGS. 8 and 9, operation of the opticalinformation recording apparatus 900 according to this example will bedescribed. First, the system control circuit 901 rotates the spindlemotor 907, and the optical head 903 focuses the laser light 870 onto thefirst information recording layer 820 on the optical disc 800 so as toreproduce information on the first information recording layer 820.Based on address reproduction information from the reproduction section904, the interference area determination section 905 determines whetherthe area, in which information is being reproduced, is the area 875 ornot. Based on the determination result, the system control section 901seeks for the optical head 903 up to a certain area in the area 875 andreproduces information in the certain area of the area 875.

Based on the reproduction information from the reproduction section 904,the recorded/unrecorded state determination section 906 determineswhether the track in the certain area in the area 875, in whichinformation is being reproduced, is in a recorded state or an unrecordedstate. When the recorded/unrecorded state determination section 906determines that the track is in an unrecorded state, some information isrecorded in the track in the certain area in the area 875 so as to placethe certain area in the area 875 into a recorded state. When therecorded/unrecorded state determination section 906 determines that thetrack is in a recorded state, it is confirmed that the certain area inthe area 875, in which information is being reproduced, is already in arecorded state. This operation is performed for the entirety of the area875.

In this manner, the area 875 is entirely placed into a recorded state,and thus acts as a recorded state area. Onto whichever position of thesecond test recording area 836 the laser light 870 may be focused, thelight transmittance of the area 875 of the first information recordinglayer 820, through which the laser light for recording information inthe second test recording area 836 passes, can be uniform. Accordingly,whichever portion of the second test recording area 836 of the secondinformation recording layer may be used for test recording, the amountof the laser light reaching the second test recording area 836 is thesame. Thus, accurate recording conditions can be obtained.

Example 4

In Example 3, an operation for placing the area 875, of the firstinformation recording layer, through which the laser light for recordinginformation in the second test recording area 836 passes, into arecorded state area was described. In this example, a specific exampleof an operation for placing the entirety of the area of the firstinformation recording layer, through which the laser light for recordinginformation in the second test recording area passes, into an unrecordedstate will be described.

FIG. 10 shows a format of an optical disc 1000 according to Example 4.

The optical disc 1000 includes a first information recording layer 1020,a second information recording layer 1030, and a separation layer 1050for separating the first information recording layer 1020 and the secondinformation recording layer 1030 from each other.

The first information recording layer 1020 includes a firstreproduction-only area 1022 and a first recording and reproduction area1024. The first recording and reproduction area 1024 includes a firsttest recording area 1026 and a first data recording area 1028. In FIG.10, the first information recording layer 1020 includes the firstreproduction-only area 1022, the first test recording area 1026, and thefirst data recording area 1028 in that order from the inner portionthereof.

The second information recording layer 1030 includes a secondreproduction-only area 1032 and a second recording and reproduction area1034. The second recording and reproduction area 1034 includes a secondtest recording area 1036 and a second data recording area 1038. An area1033 between the second reproduction-only area 1032 and the second testrecording area 1036 is for example, an unused area which has not beenused. In FIG. 10, the second information recording layer 1030 includesthe second reproduction-only area 1032, the unused area 1033, the secondtest recording area 1036, and the second data recording area 1038 inthat order from the inner portion thereof.

In the optical disc 1000, the first recording and reproduction area 1024includes a unrecorded state area 1075 of the first information recordinglayer 1020. Laser light 1070, used for recording information in thesecond test recording area 1036, passes through the unrecorded statearea 1075. The unrecorded state area 1075 is entirely in an unrecordedstate. The length of the unrecorded state area 1075 is δ+a+δ. Namely,the recorded state area 1075 includes an area corresponding to thesecond test recording area 1036 having the length a and two areasrespectively extending from an inner end and an outer end of theabove-mentioned area toward the center of the disc and the outerperiphery of the disc, each extending area having length δ.

As shown in FIG. 10, the area, of the first recording and reproductionarea 1024 including the area corresponding to the second test recordingarea 1036 having the length a and two areas respectively extending froman inner end and an outer end of the above-mentioned area toward thecenter of the disc and the outer periphery of the disc, each extendingarea having length δ (i.e., the area of the first information recordinglayer 1020 having the length of δ+a+δ) is in an unrecorded state at thetime of test recording.

The information for calculating optimum recording conditions based onthe result of the test recording may be recorded in an arbitrary area ofthe first information recording layer 1020 and the second informationrecording layer 1030. In this case, the information for calculating theoptimum recording conditions are, for example, information formultiplying the recording conditions in an unrecorded state by a certaincoefficient based on, for example, the difference in the amount oftransmitted light between the unrecorded state and the recorded state.In this example, the entirety of the area of the first informationrecording layer 1020, through which the laser light for recordinginformation in the second test recording area 1036 passes, is in anunrecorded state. Accordingly, the recording conditions obtained in sucha circumstance have a possibility of not being optimum for recordinginformation in the second test recording area 1038 using the laser lightwhich has passed through the first recording information recording layer1020 having information recorded thereon.

Hereinafter, a specific example of an operation for multiplying therecording conditions in an unrecorded state by a certain coefficientbased on the difference in the amount of transmitted light between theunrecorded state and the recorded state will be described.

In the case of an optical disc in which the amount of transmitted lightin a recorded state is s times the amount of transmitted light in anunrecorded state, where the optimum recording power obtained byperforming test recording in an unrecorded state is Pm, the optimumrecording power Pk in a recorded state can be calculated as follows.

Pk=Pm/s

Here, “s” is defined as the transmittance correction coefficient. Bysuch a calculation, even when information is not recorded in a specificarea of the first information recording layer 1020 in advance, theoptimum recording power in the case where the area of the firstinformation recording layer 1020, through which the laser light passes,is in a recorded state can be estimated. In the case where it istime-consuming to form the recorded state area 875 in the firstinformation recording layer 1020 as in Example 3, the optimum recordingconditions can be calculated as in this example, instead of directlyobtaining the optimum recording conditions as in Example 3.

In the case where there is a possibility that the first informationrecording layer 1020 and the second information recording layer 1030 inthis example are positionally offset with respect to each other, it ispreferable to keep the unrecorded state area 1075 having the lengthδ′+a+δ′ unrecorded at the time of test recording as described in Example2.

In this example, it is more preferable to record the transmittancecorrection coefficient s for determining the optimum recording power ina specific area in the optical disc 1000 (for example, the firstreproduction-only area 1022 or the second reproduction-only area 1032).In this case, even when the transmittance correction coefficient isdifferent among different optical discs, the optical disc recordingapparatus can immediately learn the coefficient when an optical disc ismounted on the optical disc recording apparatus. Therefore, the timerequired to start actually recording information can be shortened.

In this example, the unrecorded state area at the time of test recordingmay be a recording prohibited area where information is never recorded.Alternatively, the unrecorded state area may be a mirror area which doesnot have any guide grooves for tracking servo control.

Example 5

In Examples 1 through 4, the recording and reproduction area of thefirst information recording layer includes a light spot of the laserlight. The present invention is not limited to such a format. In thisexample, a format where the reproduction-only area of the firstinformation recording layer includes a light spot of the laser lightwill be described.

FIG. 11 shows a format of an optical disc 1100 according to Example 5.

The optical disc 1100 includes a first information recording layer 1120,a second information recording layer 1130, and a separation layer 1150for separating the first information recording layer 1120 and the secondinformation recording layer 1130 from each other.

The first information recording layer 1120 includes a firstreproduction-only area 1122 and a first recording and reproduction area1124. The first recording and reproduction area 1124 includes a firsttest recording area 1126 and a first data recording area 1128. In FIG.11, the first information recording layer 1120 includes the firstreproduction-only area 1122, the first test recording area 1126, and thefirst data recording area 1128 in that order from the inner portionthereof.

The second information recording layer 1130 includes a secondreproduction-only area 1132, a third reproduction-only area 1133, and asecond recording and reproduction area 1134. The second recording andreproduction area 1134 includes a second test recording area 1136 and asecond data recording area 1138. In FIG. 11, the second informationrecording layer 1130 includes the second reproduction-only area 1132,the second test recording area 1136, the third reproduction-only area1133, and the second data recording area 1138 in that order from theinner portion thereof.

As shown in FIG. 11, the first reproduction-only area 1122 of the firstinformation recording layer 1120 is structured so as to include an area(light spot) 1175 through which laser light 1170 for recordinginformation in the second test recording area 1136 passes. The length ofthe area 1175 is δ+a+δ. Namely, the area 1175 includes an areacorresponding to the second test recording area 1136 having the length aand two areas respectively extending from an inner end and an outer endof the above-mentioned area toward the center of the disc and the outerperiphery of the disc, each extending area having length δ. Thus, atwhichever position of the second test recording area 1136 test recordingmay be performed, the laser light for recording information in thesecond test recording area 1136 is the laser light which has passedthrough the first reproduction-only area 1122. As a result, therecording conditions are prevented from being dispersed depending on theposition at which the test recording is performed.

In this example, as described in Example 4, it is more preferable tocalculate the optimum recording conditions based on the result of thetest recording. Thus, the optimum recording conditions for the casewhere the laser light passes through the first recording andreproduction area 1124, which is in a recorded state with a recordingmark array being formed, can be estimated.

In the case where there is a possibility that the first informationrecording layer 1120 and the second information recording layer 1130 arepositionally offset with respect to each other, the firstreproduction-only area 1122 is located so as to have the length δ′+a+δ′,which is the length of the area 1175 of the first information recordinglayer 1120, as described in Example 2.

Example 6

In Examples 1 through 5, information is recorded in the test recordingarea of the second information recording layer in order to perform testrecording of the second information recording layer. When data isrecorded in the recording and reproduction area of the secondinformation recording layer, as well as at the time of test recordingdescribed in Examples 1 through 5, there is a possibility of the signalquality for reproducing the recorded signal being lowered. The reason isthat when the laser light used for recording passes through both thereproduction-only area and the recording and reproduction area, theamount of laser light reaching the recording and reproduction area ofthe second information recording layer is different depending on whichone of the above two areas the laser light has passed through. As aresult, accurate recording cannot be performed.

In this example, a specific example of recording information in therecording and reproduction area of the second information recordinglayer will be described.

FIG. 12 shows a format of an optical disc 1200 according to Example 6.

The optical disc 1200 includes a first information recording layer 1220,a second information recording layer 1230, and a separation layer 1250for separating the first information recording layer 1220 and the secondinformation recording layer 1230 from each other.

The first information recording layer 1220 includes a firstreproduction-only area 1222 and a first recording and reproduction area1224. In FIG. 12, the first information recording layer 1220 includesthe first reproduction-only area 1222 and the first recording andreproduction area 1224 in that order from the inner portion thereof.

The second information recording layer 1230 includes a secondreproduction-only area 1232 and a second recording and reproduction area1234. In FIG. 12, the second information recording layer 1230 includesthe second reproduction-only area 1232 and the second recording andreproduction area 1234 in that order from the inner portion thereof.

As shown in FIG. 12, the first reproduction-only area 1222 is preferablysmaller than the second reproduction-only area 1232 of the secondinformation recording layer 1230.

In FIG. 12, the start point of the first recording and reproduction area1224 is located closer to the center of the disc than the start point ofthe second recording and reproduction area 1234 by length δ. Owing tosuch a structure, in whichever portion of the second recording andreproduction area 1234 information may be recorded, the first recordingand reproduction area 1224 includes an area 1275 of the firstinformation recording layer 1220 through which the laser light forrecording information in the second recording and reproduction area 1234passes. Therefore, the second recording and reproduction area 1234 isonly influenced by the first recording and reproduction area 1224 and isnot influenced by the first reproduction-only area 1222. Thus,information can be accurately recorded in the second recording andreproduction area 1234.

In the case where there is a possibility that the first informationrecording layer 1220 and the second information recording layer 1230 arepositionally offset with respect to each other, the start point of thefirst recording and reproduction area 1224 and the start point of thesecond recording and reproduction area 1234 are preferably offset withrespect to each other by δ′ as described in Example 2.

In FIG. 12, the size of the first reproduction-only area 1222 may bezero. In this case, it is not necessary to form a phase pit for thefirst reproduction-only area 1222 at the time of production of the firstinformation recording layer 1200. Thus, the production process of thedisc can be simplified.

Example 7

In Examples 1 through 6, there are two information recording layers. Thepresent invention is not limited to this. According to the presentinvention, the number of information recording layers may be three ormore.

FIG. 13 shows a format of an optical disc 1300 according to Example 7 ofthe present invention.

The optical disc 1300 is obtained by expanding the optical disc inExample 1, and has a different format from that of the optical disc inExample 1. The optical disc 1300 includes N number of informationrecording layers. In FIG. 13, among the N number of informationrecording layers, three information recording layers i, j and k eachhave a reproduction area in order to obtain accurate recordingconditions by the test recording.

In this example, a first information recording layer 1310 is the i′thlayer, a second information recording layer 1320 is the j′th layer, athird information recording layer 1330 is the k′th layer, from the laserincidence side of the disc. The distance between the first informationrecording layer 1310 and the second information recording layer 1320 isdij, the distance between the second information recording layer 1320and the third information recording layer 1330 is djk, and distancebetween the first information recording layer 1310 and the thirdinformation recording layer 1330 is dik.

The first information recording layer 1310 includes a firstreproduction-only area 1312 and a first recording and reproduction area1314. The first recording and reproduction area 1314 includes a firsttest recording area 1316 and a first data recording area 1318.

The second information recording layer 1320 includes a secondreproduction-only area 1322 and a second recording and reproduction area1324. The second recording and reproduction area 1324 includes a secondtest recording area 1326 and a second data recording area 1328.

The third information recording layer 1330 includes a thirdreproduction-only area 1332 and a third recording and reproduction area1334. The third recording and reproduction area 1334 includes a thirdtest recording area 1336 and a third data recording area 1338.

In this case, the start point of the first recording and reproductionarea 1312 is at least δij away from the start point of the second testrecording area 1326, and is at least δik away from the start point ofthe third test recording area 1336. The start point of the secondrecording and reproduction area 1324 is at least δjk away from the startpoint of the third test recording area 1336. Here,

δij=dij·tan(sin⁻¹(NA/n)),

δik=dik·tan(sin⁻¹(NA/n)), and

δjk=djk·tan(sin⁻¹(NA/n)),

where NA is the numerical aperture of an objective lens for focusinglaser light 1370, and n is the refractive index of the separation layerbetween the first information recording layer 1310 and the secondinformation recording layer 1320 and of the separation layer between thesecond information recording layer 1320 and the third informationrecording layer 1330.

Owing to such a structure, the laser light 1370 for recordinginformation in the second test recording area 1326 passes through onlythe first recording and reproduction area 1314 when passing through thefirst information recording layer 1310. The laser light 1370 forrecording information in the third test recording area 1336 passesthrough only the first recording and reproduction area 1314 when passingthrough the first information recording layer 1310 and only the secondrecording and reproduction area 1324 when passing through the secondinformation recording layer 1320.

Even when the information recording layer as a target is, for example,between the first information recording layer 1310 and the secondinformation recording layer 1320 as in this example or at an arbitraryposition, substantially the same effect as that in Example 1 isprovided, as long as the second information recording layer 1320 isfarther from the incidence surface than the first information recordinglayer 1310, and an area of the first information recording layer 1310,through which the laser light 1370 for recording information in thesecond test recording area 1326 passes, is entirely a recording andreproduction area.

Example 8

FIG. 14 shows a format of an optical disc 1400 according to Example 8 ofthe present invention.

The optical disc 1400 includes a first information recording layer 1420,a second information recording layer 1430, and a separation layer 1450for separating the first information recording layer 1420 and the secondinformation recording layer 1430 from each other.

The first information recording layer 1420 includes a firstreproduction-only area 1422, a first recording and reproduction area1424 and a second reproduction-only area 1429. The first recording andreproduction area 1424 includes a first test recording area 1426 and afirst data recording area 1428. In FIG. 14, the first informationrecording layer 1420 includes the first test recording area 1426, thefirst reproduction-only area 1422, the first data recording area 1428,and the second reproduction-only area 1429 in that order from the innerportion thereof. The first information recording layer 1420 includes afirst lead-in area 1425 and a first lead-out area 1427. The firstlead-in area 1425 includes the first test recording area 1426 and thefirst reproduction-only area 1422. The first lead-out area 1427 includesthe second reproduction-only area 1429.

The second information recording layer 1430 includes a thirdreproduction-only area 1432, a second recording and reproduction area1434, a fourth reproduction-only area 1433, and a fifthreproduction-only area 1439. The second recording and reproduction area1434 includes a second test recording area 1436 and a second datarecording area 1438. In FIG. 14, the second information recording layer1430 includes the third reproduction-only area 1432, the second testrecording area 1436, the fourth reproduction-only area 1433, the seconddata recording area 1438, and the fifth reproduction-only area 1439 inthat order from the inner portion thereof. The second informationrecording layer 1430 includes a second lead-in area 1435 and a secondlead-out area 1437. The second lead-in area 1435 includes the thirdreproduction-only area 1432, the second test recording area 1436, andthe fourth reproduction-only area 1433. The second lead-out area 1437includes the fifth reproduction-only area 1439.

In this example, when priority is put on easy management of the opticaldisc 1400, it is preferable to have the format shown in FIG. 14 in whichthe first data recording area 1428 and the second data recording area1438 have an equal size. The optical disc 1400 includes the firstlead-in area 1425 and the second lead-in area 1435 internally to thefirst data recording area 1428 and the second data recording area 1438,respectively. The optical disc 1400 also includes the first lead-outarea 1427 and the second lead-out area 1439 externally to the first datarecording area 1428 and the second data recording area 1438,respectively. The first test recording area 1426 is located internallyto the first lead-in area 1425, and the second test recording area 1436is located internally to the second lead-in area 1435.

The first test recording area 1426 and the second test recording area1436 are positionally offset with respect to each other by length δ ormore. The first reproduction-only area 1422 includes a non-uniform lightprevention area 1475 of the first information recording layer 1410through which laser light 1470 for recording information in the secondtest recording area 1436 passes. The length of the area 1475 isrepresented by δ+a+δ. The non-uniform light prevention area 1475prevents the laser light 1470 incident thereon from transmittingtherethrough in a non-uniform shape.

The non-uniform light prevention area 1475 is, for example, areproduction-only area.

Alternatively, the non-uniform light prevention area 1475 may be arecording prohibited area or a mirror area. Owing to such a structure,at whichever position of the second test recording area 1436 testrecording may be performed, the obtained recording conditions are notdispersed. Moreover, owing to such a structure, the first lead-in area1425 of the first information recording layer 1420 and the secondlead-in area 1435 of the second information recording layer 1430 canhave identical start points, termination points and capacities. Thefirst data recording area 1428 of the first information recording layer1420 and the second data recording area 1438 of the second informationrecording layer 1430 can have identical start points, termination pointsand capacities. The first lead-out area 1427 of the first informationrecording layer 1420 and the second lead-out area 1437 of the secondinformation recording layer 1430 can have identical start points,termination points and capacities. Therefore, defect management andrecording information management of the optical disc 1400 areadvantageously easy. Substantially the same effect is provided when thefirst test recording area 1426 is located in the first lead-out area1427 and the second test recording area 1436 is located in the secondlead-out area 1437.

The positions of the areas and the shape of the disc used in the aboveexamples are not limited to those described above, and may be of anyappropriate form in accordance with the medium itself or the recordingand reproduction apparatus.

INDUSTRIAL APPLICABILITY

As described above, according to an optical information recording mediumof the present invention, an area of the first information recordinglayer, through which laser light passes, is entirely placed into arecorded state or an unrecorded state at the time of test recording ofthe second information recording layer. Therefore, accurate recordingconditions can be obtained by the test recording.

According to an optical information recording medium of the presentinvention, an area of the first information recording layer, throughwhich laser light passes, is entirely placed into a reproduction-onlyarea or a recording and reproduction area at the time of test recordingof the second information recording layer. Therefore, accurate recordingconditions can be obtained by the test recording.

According to an optical information recording medium of the presentinvention, the reproduction-only area of the first information recordinglayer is made smaller than the reproduction-only area of the secondinformation recording layer. Therefore, information can be accuratelyrecorded anywhere in the recording and reproduction area of the secondinformation recording layer.

According to an optical information recording medium of the presentinvention, when recording information in the recording and reproductionarea of the second information recording layer, an area of the firstinformation recording layer, through which laser light passes, isentirely placed into a reproduction-only area or a recording andreproduction area. Therefore, information can be accurately recorded inthe recording and reproduction area.

According to an optical information recording method of the presentinvention, information is recorded in an area of the recording andreproduction area of the first information recording layer through whichlaser light passes before test recording of the second informationrecording layer. Therefore, accurate recording conditions can beobtained by the test recording.

According to a recording and reproduction method of the presentinvention, in the case where an area of the recording and reproductionarea of the first information recording layer through which laser lightpasses is in an unrecorded state at the time of test recording of thesecond information recording layer, optimum recording conditions arecalculated based on the test recording result. Therefore, accuraterecording conditions can be obtained.

In a medium according to the present invention, one of thereproduction-only area and the recording and reproduction area of thefirst information recording layer includes an area through which laserlight for recording information in the test recording area of the secondinformation recording layer passes. The laser light for recordinginformation in the test recording area of the second informationrecording layer has passed through the reproduction-only area or therecording and reproduction area. Accordingly, the laser light forrecording information in the test recording area of the secondinformation recording layer is not influenced by the difference betweenthe amount of light passing through the reproduction-only area of thefirst information recording layer and the amount of light passingthrough the recording and reproduction area of the first informationrecording layer. As a result, accurate recording conditions can beobtained using the test recording area of the second informationrecording layer.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area passes,extends outward from an outer end of an area of the first informationrecording layer corresponding to the test recording area by a length δ,the length δ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area passes,extends outward from the outer end of the area of the first informationrecording layer corresponding to the test recording area by a length δ′,the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

Accordingly, even when there is a non-negligible offset or eccentricityin the relative positions of the information recording layers, accuraterecording conditions for the second information recording layer can beobtained at the time of test recording of the second informationrecording layer, with no influence of the difference in the amount oflight passing through the first information recording layer.

It is preferable to form an area of the second information recordinglaser, extending from the end of at least the test recording area by δ(in the case where there is a non-negligible offset or eccentricity inthe relative positions of the information recording layers, by δ′) intoa data recording area. This is preferable in order to expand the datarecording area.

According to the medium of the present invention, a prescribed area ofthe first information recording layer, which is entirely in a recordedstate or an unrecorded state, includes an area through which the laserlight for recording information in the test recording area of the secondinformation recording layer passes. The area of the first informationrecording layer, through which the laser light for recording informationin the test recording area of the second information recording layerpasses, is entirely either in a recorded state or in an unrecordedstate. Accordingly, the laser light for recording information in thetest recording area of the second information recording layer is notinfluenced by the difference in the amount of light caused by theexistence of both a recorded state area and an unrecorded state area. Asa result, accurate recording conditions can be obtained using the testrecording area of the second information recording layer.

The prescribed area which is entirely in an unrecorded area is, forexample, a recording prohibited area, a mirror area, or a lead-in area.

Regarding a second optical information recording medium according to thepresent invention, the area of the first information recording layer,through which the laser light for recording information in the testrecording area of the second information recording layer passes, extendsoutward from an outer end of an area of the first information recordinglayer corresponding to the test recording area by a length δ, the lengthδ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

Regarding the second optical information recording medium according tothe present invention, the area of the first information recordinglayer, through which the laser light for recording information in thetest recording area of the second information recording layer passes,extends outward from the outer end of the area of the first informationrecording layer corresponding to the test recording area by a length δ′,the length δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

Owing to such a medium, even when there is a non-negligible offset oreccentricity in the relative positions of the information recordinglayers, accurate recording conditions for the second informationrecording layer can be obtained at the time of test recording of thesecond information recording layer, with no influence of the differencein the amount of light passing through the first information recordinglayer.

Regarding the second optical information recording medium according tothe present invention, it is preferable to form an area of the secondinformation recording laser, extending from the end of at least the testrecording area by δ (in the case where there is a non-negligible offsetor eccentricity in the relative positions of the information recordinglayers, by δ′) into a data recording area. This is preferable in orderto expand the data recording area.

The information for calculating the optimum recording conditions in thetest recording area are recorded in a specific area of one of aplurality of recording information layers. Accordingly, even when thetransmittance of the area of the first information recording layer,through which the laser light for recording information in the testrecording area of the second information recording layer passes, isdifferent from the transmittance of the area of the first recordinginformation layer, through which the laser light for recordinginformation in the recording and reproduction area of the secondinformation recording layer passes, accurate recording conditions can becalculated for one of the layers as long as the recording conditions ofthe other layer can be obtained. As a result, a recording andreproduction apparatus for starting the optical information recordingmedium can immediately learn a method of calculation which is determinedfrom the difference between the amount of light transmitted through anunrecorded state area and the amount of light transmitted through arecorded state area. Accordingly, accurate recording conditions can beobtained immediately after the optical information recording medium ismounted on the recording and reproduction apparatus.

According to this medium, one of the reproduction-only area and therecording and reproduction area of the first information recording layerincludes an area through which laser light for recording information inthe recording and reproduction area of the second information recordinglayer passes. The laser light for recording information in the recordingand reproduction area of the second information recording layer haspassed through the reproduction-only area or the recording andreproduction area. Accordingly, the laser light for recordinginformation in the recording and reproduction area of the secondinformation recording layer is not influenced by the difference betweenthe amount of light passing through the reproduction-only area of thefirst information recording layer and the amount of light passingthrough the recording and reproduction area of the first informationrecording layer. As a result, accurate recording conditions can beobtained using the recording and reproduction area of the secondinformation recording layer.

The area of the first information recording layer, through which thelaser light for recording information in the recording and reproductionarea of the second information recording layer passes, extends outwardfrom an outer end of an area of the first information recording layercorresponding to the recording and reproduction area by a length δ, thelength δ being represented by:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The area of the first information recording layer, through which thelaser light for recording information in the recording and reproductionarea of the second information recording layer passes, extends outwardfrom the outer end of the area of the first information recording layercorresponding to the recording and reproduction area by a length δ′, thelength δ′ being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

In an optical information recording and reproduction medium according tothe present invention, the size of the reproduction-only area of thefirst information recording layer can be zero, such that an areainfluenced by the reproduction-only area of the first informationrecording layer is minimized at the time of recording in the recordingand reproduction area of the second information recording layer. Thus,information can be recorded accurately on the second informationrecording layer.

Owing to this medium, the necessity of forming a phase pit in thereproduction-only area at the time of production of the firstinformation recording layer is eliminated. Thus, the production processof the disc substrate can be simplified.

The lead-in areas or the lead-out areas of corresponding informationrecording layers include a first test recording area, a recording andreproduction area, and a second test recording area. Therefore,recording conditions of different information recording layers can beobtained with only the lead-in areas or the lead-out areas. In thiscase, the non-uniform light prevention area of the first informationrecording layer includes an area of the first information recordinglayer through which laser light for recording information in the testrecording area of the second information recording layer passes.

The non-uniform light prevention area is, for example, areproduction-only area.

The non-uniform light prevention area is, for example, an area formed ofat least one of the group consisting of a reproduction-only area, arecording prohibited area, and a mirror area.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area of thesecond information recording layer passes, extends outward from an outerend of an area of the first information recording layer corresponding tothe test recording area by a length δ, the length δ being representedby:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area of thesecond information recording layer passes, extends outward from theouter end of the area of the first information recording layercorresponding to the test recording area by a length δ′, the length δ′being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

Accordingly, even when there is a non-negligible offset or eccentricityin the relative positions of the information recording layers, accuraterecording conditions for the second information recording layer can beobtained at the time of test recording of the second informationrecording layer, with no influence of the difference in the amount oflight passing through the first information recording layer.

According to the method of the present invention, before information isrecorded in the test recording area of the second information recordinglayer, information is stored in an area of the first informationrecording layer through which laser light for recording information inthe test recording area of the second information recording layerpasses. Accordingly, the laser light for recording information in thetest recording area of the second information recording layer is notinfluenced by the difference in the amount of light which is caused bythe first information recording layer having both a recorded state areaand an unrecorded state area. As a result, accurate recording conditionscan be obtained by test recording of the second information recordinglayer.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area of thesecond information recording layer passes, extends outward from an outerend of an area of the first information recording layer corresponding tothe test recording area by a length δ, the length δ being representedby:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area of thesecond information recording layer passes, extends outward from theouter end of the area of the first information recording layercorresponding to the test recording area by a length δ′, the length δ′being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

Owing to such a method, even when there is a non-negligible offset oreccentricity in the relative positions of the information recordinglayers, accurate recording conditions can be obtained at the time oftest recording of the second information recording layer, with noinfluence of the difference in the amount of light caused by the firstinformation recording layer having both a recorded state area and anunrecorded state area.

The information which is recorded in advance may be, for example,information obtained by modulating dummy information.

The information may be recorded in advance by a certification step.

According to the method of the present invention, optimum recordingconditions for the second information recording layer can be calculatedbased on the function and/or the state of the area of the firstinformation recording layer through which the laser light for recordinginformation in the test recording area of the second informationrecording layer passes.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area of thesecond information recording layer passes, extends outward from an outerend of an area of the first information recording layer corresponding tothe test recording area by a length δ, the length δ being representedby:

δ=d·tan(sin⁻¹(NA/n)),

where d is a distance in a thickness direction between the firstinformation recording layer and the second information recording layer;n is a refractive index of the separation layer; and NA is a numericalaperture of an objective lens for focusing the laser light to the testrecording area.

The area of the first information recording layer, through which thelaser light for recording information in the test recording area of thesecond information recording layer passes, extends outward from theouter end of the area of the first information recording layercorresponding to the test recording area by a length δ′, the length δ′being represented by:

δ′=d·tan(sin⁻¹(NA/n))+δm

where δm is a maximum positional offset distance between the firstinformation recording layer and the second information recording layer.

Owing to this method, even when there is a non-negligible offset oreccentricity in the relative positions of the information recordinglayers, accurate recording conditions can be obtained at the time oftest recording of the second information recording layer, based on thedifference between the amount of light transmitted through an unrecordedstate area of the first information recording layer and the amount oflight transmitted through a recorded state area of the first informationrecording layer.

It is preferable to record information for calculating the optimumrecording conditions in a specific area of the optical informationrecording medium.

Thus, even when the method of calculation is different medium by medium,the recording and reproduction apparatus can immediately learn themethod of calculation. Therefore, the time required for actuallyrecording information after the medium is mounted on the apparatus canbe shortened.

According to the optical information recording apparatus of the presentinvention, even when an area of the first information recording layer,through which laser light for recording information in the testrecording area of the second information recording layer passes,includes an unrecorded state area, the laser light for recordinginformation in the test recording area of the second informationrecording layer records the information in the area of the firstinformation recording layer, before recording the information in thetest recording area of the second information recording layer.Therefore, there is no influence of the difference in the amount oflight, caused by the laser light for recording information in the testrecording area of the second information recording layer passing throughan area including both a recorded state area and an unrecorded statearea. As a result, accurate recording conditions for the secondinformation recording layer can be obtained.

1. An information recording medium comprising a first recording layerand a second recording layer, wherein information is to be recorded onthe second recording layer by laser light which has passed through thefirst recording layer, the first recording layer includes a firstinternal circumference area, a first data recording area located at theouter side far from the first internal circumference area, and a firstouter circumference area located at the outer side far from the firstdata recording area, the first internal circumference area includes afirst test recording area, the second recording layer includes a secondinternal circumference area, a second data recording area located at theouter side far from the second internal circumference area, a secondouter circumference area located at the outer side far from the seconddata recording area, the second inner circumference area includes asecond text recording area, the first text recording area and the secondtext recording area are respectively located at the different radiuspositions with each other, and within the second recording layer an areadifferent from the second text recording area is located at the radiusposition wherein the first text recording area is located.
 2. Areproduction method for reproducing information from the informationrecording medium according to claim 1, the reproduction methodcomprising: reproducing at least one of a first user data recorded byusing the recording power of the first layer from the first layer and asecond user data recorded by using the recording power of the secondlayer from the second layer.
 3. A reproduction method according to claim1, the reproduction method comprising: reproducing a disk informationstored in a disk information area in the information recording medium;and reproducing the information on a recording medium based on thereproduced disc information.
 4. An information recording method forperforming a recording for the information recording medium according toclaim 1, the method comprising: determining a recording power of atleast one of the first layer and the second layer by using at least oneof the first test area and the second test area.